The Darklighter
by Hellkisses
Summary: After telling Simon that she loves him, Sizzy decide to take their relationship to the next level. But circumstances arise when Simon is losing himself to the inner Dark vampire inside of him, along with Isabelle finding that she is pregnant with Simon's baby. Now kicked out of the Clave, Isabelle has to try and help Simon maintain his humanity and keep her demon child alive.
1. Chapter 1

"Simon, I don't get this frick'n game!" Isabelle yelled exasperated whilst pushing the buttons of the play station. Simon sitting next to her wearing an orange Penny-T saying 'P.B and jelly love', a pair of bright grey jeans and sighed, "Izzy, the whole point about playing _Slender _is that you've gotta find his 8 pages without dying".

"I've been playing this game for 20 minutes and I haven't found any god damn pages!" She huffed and flicked her head, flipping away the long lock of black hair over her face. Stupid Simon, this was supposed to be a date night! If Isabelle had known that she was going to be playing a dumb video game then she wouldn't have worn her 6 inch high heels, tight purple tank top and short black leather mini skirt. A good sexy outfit put to waste. "That's because you've been wondering around in the woods instead of looking for a tunnel or a truck" Simon responded whilst resting his chin on his hand looking bored, watching her play. Izzy rolled her eyes and huffed again and squinted her eyes at the screen. _Why did he have to turn the frick'n lights off? _Her mind complained. Apparently to make it more 'fun' she remembered, she rolled her eyes again. "OH, oh look! Behind that truck!" Simon's voice sprinted in excitement as he pointed to the screen at a page. Izzy blinked and pushed the button making her go forward as she bit her tongue in concentration. "How do I get it?" she asked, _are you actually trying to win this dumb game?! _Her subconscious yelled at her, tapping her foot in disappointment. Simon got on his knees and leaned in next to Izzy leaning against her back as he brought his arm over her shoulder carefully and wrapped his hand around hers pointing her finger to one of the letter labelled buttons. The feeling of his chest on her back, no heat, no heartbeat and still it brought a chill down her spin, pricking her nerves one by one. She bit her lip and smirked to herself not looking at him, knowing he was being so sexy unintentionally was cute. Another thing she loved about her vampire boyfriend was that above the whole blood sucking, Daylighter and immortality crap, there was still that goofy nerd. Her goofy, sexy cute nerd. "You press the 'E' button" He said gently pushing her finger against the button and Izzy then looked up at the screen as the page vanished and words appeared on the screen saying '1/8 pages found'. Izzy cheered in her mind then blinked and shook her head realising how stupid that was. "Okay, you see? Now we're getting somewhere." At least he didn't sound as bored as before. She glared at him at the corner of her eye then turned her attention back to the game. "So, what is a _'Slender' _anyway?" she asked whilst punching the remote buttons concentrating on the screen. She heard Simon chuckle, "It's not 'what', it's 'who'. _Slender man _is a guy with no face who lives in the woods and drags people who enter his lands and kills them by staring at them." Simon explained quite proudly. Isabelle frowned; there were many questions she wanted to ask. Like, why doesn't he live in a haunted mansion instead? And how could you die by staring at him if he doesn't even have a face. But what came out of her mouth was, "He sounds like a rapist" she said with willingly. Simon arched his eyebrows looking up, "What do you mean by tha-SHIT! IZZY, OVER THERE!" Izzy blinked at his screaming, "What?" she asked as she turned back to the screen and gasped seeing a pale white slender figure wearing a black suit with no face staring at her from the screen. "ISABELLE!" Simon yelled at her and before he could take the control, Izzy screamed, "Motherfucker!" and grabbed her whip (which was wrapped around her arm posing as a 'Golden chain') and raised her hand then striking straight at the TV causing it to break in half and fall back from the stand. She panted loudly trying to catch her breath still in shock as the now broken TV gliched tiny electric circuits. Izzy bit down on her lip and looked to the side at Simon who was staring at the broken TV completely frozen with eyes wide in horror and his mouth wide open. _Oh shit…_Izzy looked over at the TV then down at her whip and back at Simon realizing what a completely dumbass thing she'd just done. She pressed her lips together in a hard line in guilt and leaned in poking him on the shoulder. "Um…Simon?" after a long moment of silence she watched him take a deep breath in and press his lips together as his eyes looked like they were about to pop out of his sockets as he faced her (looking like a constipated retard) then finally he cracked. "WHAT THE HELL DID YOU DO TO MY TV?!" He screamed louder than ever and Izzy flinched from the volume then looked at him giving an awkward look and shrugged, "He appeared out of nowhere, it was creepy". Simon's jaw dropped again and Izzy couldn't tell if it was in disbelief or insult as he screeched, "Yeah! But you're a frick'n shadowhunter you've seen demons pop out from under your own bed!" Izzy gave a considering look and nodded in agreement. Simon growled, "And can I ask you Iz, in what messed world is my TV a downworlder?!" Sarcasm carried his voice along with pure irritation. Izzy guessed if he were alive then she would be able to see the blood rise in his red angered face. "Oh Crap, Jordan's gonna kill me" Simon sobbed, burying his face in his hands in pure stress. Isabelle looked up and sighed feeling a bit guilty as she then looked back at the destroyed TV and then pursed her lips giving a considering face. "Well," She began as she got on her knees and faced Simon, playing seductively with the collar of his shirt, "I could find a way to make it up to you". Simon slowly raised his face from his hands and looked at her in confusion, "Say wha?" Izzy rolled her eyes and smirked as she slowly sat herself on his lap facing him and wrapping her legs around his waist whilst wrapping her arms around his neck. Simon blinked and stared at her seeming to finally get the picture as she could make out the rosey pink colour in his cheeks. She smiled as the memory of him blushing in Idris came back to her. "Wow, wow, wow, wow!" Simon repeated rapidly whilst putting his hands up in defence "Let me get this straight, you think just because you're gonna have sex with me, that will make up for the fact that you broke me and Jordan's 3,000 dollar flat screen TV?!" he stared at her in disbelief waiting for an answer and Izzy cocked her head to the side thinking to herself for moment then looking back at him and nodding, "Yep, pretty much" she replied cutely. After a moment of silent, Simon closed his mouth and shrugged, "Good enough for me" he mumbled and Izzy let out a little giggle as she leaned her face in and kissed his lips. At first it was a slow, soft and lingering kiss, then the heat picked up as he wrapped his arms tightly around her waist and she grinned grasping his hair fiercely. Izzy felt quite proud of herself for teaching Simon how to improve on his kissing. Now he used a really good use of lips, mouth, teeth and tongue. His hands began to wander as he carefully began to caress her back and she shivered a little in response as she opened her mouth and began to play with his tongue. He groaned in response as his fingers gently knotted in her hair and his other hand traveled down her back and began to stroke her bare leg all the way up to her waist going underneath her skirt. She let out a little gasp through the kiss and quickly without any hesitation she pulled off his stupid T shirt and threw it away. She bit his bottom lip teasingly and she felt his hands tighten around her hair and on her leg as the kiss become a fiery and wild heat. Suddenly they heard the door open as they broke the kiss and both looked at the hallway to see Jordan carrying Maya in his arms with her legs wrapped around his waist, her hands pulling off his jacket and shirt rapidly and both sharing a fierce and hot kiss. Izzy remembered Simon telling her that Jordan was taking Maya to the Preaetor Lupus moonwalk ceremony. _Well _Izzy thought to herself sarcastically _I hope that's not part of the ceremony. _Clearly not noticing them against the sofa, Simon cleared his throat loudly and Jordan broke away from Maya as they both turned around and looked at them. Their eyes both widened and Maya gasped as she gave Jordan an 'Ahem!' look and getting the message he let her go and she landed on the ground pulling back her hair trying to disguise what was happening. "Uh, hey guys…" Maya said awkwardly, her hair was a mess, there was lip gloss smudged over her mouth and two of the buttons of her blue shirt were undone revealing her neon green bra (which by the looks of it she hadn't noticed) "I uh," She tried to mask away as she flushed "Thought you guys were having a date night?" _Me too_ Izzy thought in her head and then rolled her eyes as she got off Simon's lap and huffed sitting back down next to him. She looked over at him and smiled seeing him trying to calm himself down grabbing his T shirt and putting it back on, the bright red blush still painting his cheeks. After pulling on his shirt he glanced at her and she winked sensually at him and he gulped then looked quickly back to Jordan. _Cutey_ Izzy thought and giggled to herself. "The um," Jordan muttered through heavy breathing "ceremony finished early" He said nodding to himself in satisfaction at his excuse. "Yeah I can see that" Simon responded, sarcasm seeking his voice. Jordan glanced down at Maya and saw her giving him a 'Seriously?' look with her arms crossed over her chest. Jordan gulped nervously then looked to the living room and his eyes suddenly widened in shock and his jaw fell. Simon looked into his direction and groaned in exhaustion knowing that he was looking at the destroyed TV. Maya then followed his gaze and gasped clasping a hand over her mouth in shock. "WHAT THE HELL HAPPENED TO MY TV?!" Jordan yelled helplessly as he grasped his own hair in panic. Simon sighed and then gave Isabelle a guilt look and Jordan and Maya both looked at Izzy in shock. After a moment of long awkward silence, Izzy shrugged and gave a charming smile and a little wave "Hi".

**Hey guys,**

**My name's Erica and I would like to thank you for reading the first part of my Sizzy fanfiction. I chose to do Sizzy since they were always my favourite couple and I always wanted to give them their own story. I know it's quite long for a prologue but once I start typing I just can't stop. Which means the first chapter will be out quicker than you know. I pretty promise. **

**Thanks again, XOXO**


	2. The Darklighter- Chapter 1

Chapter 1

The next morning

With heavy tired eyes, Izzy slowly twisted the handle of the Institute doors and opened them then rubbing her head in pain from the loud squeaking noise. Couldn't Maryse have put a silent rune on them or something? Exhaustibly dragging her tired body to the library, Izzy fell back on the sofa and gave a long sigh of relief as she laid back her head and closed her eyes. She felt Church land on her lap and curl himself in a fluffy fat ball and she stroked him half asleep.

"HELP! HE'S GONNA KILL ME!" Izzy jumped as she was awoken by the screams of a young boy. Church hissed then sprinted out of her lap running away. Izzy frowned and looked at the open doors of the library.

"MAX! COME BACK HERE YOU LITTLE TWERP!" This time the voice older and Izzy rolled her eyes realizing that the voices belonged to Alec and Max. She stood up and her head spun a bit as she blinked trying to fully wake up. Damn she was up to late, 2 hours playing _Slender _and the last 4 watching _Star Wars _with Simon, Jordan and Maya. It wasn't a bad movie as she thought it would be and for some reason Luke and Leiah reminded her of Jace and Clary. But even after all that, the only time she got close to sleeping with Simon was falling asleep with him in his bed. They'd been dating for 3 months now and they still haven't done anything. Izzy got annoyed at the thought and then managed to stand up without falling to the ground. She turned her head as both her brothers ran into the library. Alec was chasing Max going up the tables, under the tables and over the sofa. After noticing his sister Max yelled, "Izzy! Help!" she quickly dashed towards her and hid behind his big sister holding tightly onto her hand. Alec's face was red with anger as he stared down at his little brother with rage, "Max! Stop being such a wuss and come here!" he yelled. "Forget it!" Max snapped back still hiding behind Izzy, "I'd rather keep eyes in my sockets, thank you very much!" Isabelle blinked and raised her hands in annoying defence trying to break the anger going on between her juvenile brothers. "Wow, wow, wow!" She yelled "What the hell is going on here?! Alec?" Alec glanced once again at Max then up to his sister and he crossed his arms sulking like he used to when he was 10. "Well," Simon began rolling his eyes "I walked into my room and I couldn't find my _stele _so I went into Max's room to ask if he'd seen it and guess what I walk in to find?!" He paused as his voice rose on the final point and Isabelle raised her eyebrows impatiently at him waiting for an answer. Alec continued, "I walk in and find Max using my _stele _to draw one of his dumb cartoons on his arm!" Izzy blinked in surprise and then looked back down at Max who was still glaring at Alec from behind her. "No!" He protested, "I was trying to draw a _Fairy tail _rune like one of the mages to see what would happen!" Alec moaned and pulled his hair, "It's a frick'n comic book Max!"

"Uh it's a Manga actually" Max snapped back sticking his tongue out at him. Alec growled then jumped over the couch and marched towards Max like an ogre. Max screamed and hugged his sister, "Izzy, help me!" Isabelle rolled her eyes and just when Alec was about to grab Max she punched him in the nose. Alec whaled and covered his nose as he stumbled back and landed on the couch groaning in pain. Izzy looked down and she could see Max grinning and giggling like a little troll and she glared at him, "Hey, I can do the same thing to you, brat." Hearing her words, Max blinked and looked up at her and coming to realise she was serious his grin vanished and he looked scared then looked the other way whistling to himself. With his hand still covering his nose, Alec made an attempt to hold back the tears of pain in his eyes as he mumbled loudly, "What the fu-?!" Izzy's eyes widened as a warning for him to keep his mouth shut and not swear in front of Max. He panted, "What the hell was that for?!" Isabelle rolled her eyes and crossed her arms over her chest giving her big brother an unimpressed look. "Jesus Christ Alec, he's 10 years old. By the Angel, you're supposed to be setting a good example for him not threaten to kill him every time he pisses you off."

"Yeah, but that doesn't mean you had to punch in the God damn nose!" Alec whined and Izzy looked up thinking and then shrugged, "Meh, it was the first thing that came to my mind." Alec rolled his eyes and groaned which Izzy couldn't tell if it was in annoyance or pain. "And besides," she continued "You know you shouldn't get him scared like that, unless you want him to have another asthma attack." She gave Alec the 'guilt' look and he seemed to have sucked it in and he rolled his eyes in defeat. He stood up and Isabelle looked down at Max and flicked her head to the direction of the door telling him it was okay to go and play. Max nodded at her and then slowly began to walk out and he passed Alec they exchanged a typical 'This isn't over' brotherly look as Max quickly skidded out of the library. Alec sighed and crossed his arms over his lightly muscled chest and looked back at his sister. Isabelle cocked her head to the side, "What are _you _doing here anyway?" she asked. 4 months ago, Alec had moved in with Magnus in their luxury apartment in Brooklyn whilst Isabelle still lived in the institute with her younger brother Max and her parents (Although Robert was mostly busy because of the role of Inquisitor) Alec shrugged, "I came in because I forgot my _stele _here from my last visit. Plus I wanted to check on how everything was going on with you guys since Clary and Jace are still in Idris." That's right, Clary and Jace travelled to Idris 5 days ago for their Honey moon. It's a good thing Amatis had spare bedrooms in the Graymark manor.

Alec flicked his head making the locks of black hair that were covering his bright blue flip to a side fringe. "But," He began as he studied her outfit, smudged mascara, knotty hair and dark circles under eyes, "It looks like checked for you in the wrong place." His voice carried the stereotypical overly protective big brother concern. Isabelle hated it when he played that card. She huffed, rolling her eyes and crossed her arms getting ready for the one and only 'Alec the-pain-in-the-ass Inquisitor'. "Where were you last night, Iz?" He asked sounding all superior. Damn, if he were more bulky and had stubbles he could their father. Izzy shivered at the idea of having to have this conversation with Robert. It's these moments she thanks him for hardly being around. Isabelle sighed and then smiled innocently at her big brother and said, "I was on a date with Simon. Well, if by date you mean playing a dumb video game for 2 hours, crashing a 3,000 dollar flat screen, making out for 2 seconds then having a double date with cutest werewolves ever watching _Star Wars_ then yeah…I was on a date." Isabelle sounded a bit disappointed by her explanation of the previous but hey, that's that (Unfortunately). Alec frowned, "Wait, you went to Simon and Jordan's apartment for a _date?" _He sounded partially shocked and quite honestly, she didn't blame him. For Isabelle Lightwood a date meant going to a night club and dancing her ass off with a guy then getting drunk and having sex back at his apartment. But last night, that wasn't a date, it was a playdate! Isabelle sighed softly in embarrassment and then leaned against the book case, "Yeah, yeah and before you start coming to conclusions, nothing happened. I fell asleep whilst watching the movie and Simon slept together on his bed. And the last time I checked, whenever I wake up next to a guy and I'm fully dressed with no alcohol on the floor it usually means nothing happened." Isabelle looked away and sighed in disappointment. Alec raised his eyebrows in surprise, "Well, well, the day has finally come where a guy doesn't want to sleep with the beautiful and yet irresponsible Isabelle Lightwood, ladies and gentlemen." He teased and Isabelle could hear the slight humour in his voice and she growled at him. "Oh piss off, Alec! Besides I'd like to know how it is with you and Magnus when you're getting your gay bay on." At that Alec's laughter faded and Izzy could see the bright blush paint his cheeks and she grinned in victory. Alec hated talking about his sexuality in front of his baby sister, but honestly she was the only girl he could ever talk to and he knew it. Alec flushed and his lips pressed in a hard line, "This is not about me Iz!" he mumbled looking at the ground and Izzy laughed as she walked up to him and gave him a sweet little sister hug. "Oh don't worry Buttercup," she teased and smiled at him "You know I'm just kidding." She poked his nose and after a moment he rolled his and shrugged then the corner of his mouth quirked up a bit into a small smile showing his dimples. He really did look just like Robert. "And anyway!" She said in a cheered voice, "Simon and I aren't sealing the deal until he's fully prepared." She grinned and leaned in, whispering, "And trust me, I'll make sure he's absolutely prepared." Alec whined and gave a bit of a disturbed look at her and then shook his head, "Only you Isabelle Lightwood, only you."


	3. Chapter 2

Chapter 2

Isabelle was awoken by the sound of the kettle in Jordan's apartment. She'd come by to apologise for the whole broken TV thing, since last night they had to watch _Star Wars _on Simon's laptop. But the real reason was because she needed to talk to Simon, to know why nothing happened last night.

Slowly Isabelle rubbed her eyes then opened them and looked over the arm chair of the couch to see Simon in the kitchen. "What are you doing?" she asked whilst trying sit up and he looked startled then turned around and sighed in relief. "Just making some coffee" He responded and she could hear the chill in his voice. Simon frowned, "Wait, what are you doing here?" Isabelle leaned against the couch and shrugged, "I came to see you, but when I got here Jordan told me you were at band practice. So, he said I could wait here 'til you got back and I guess I dozed off." She said then let out a little yawn then pulled back her hair. Simon nodded and then turned his expression back to the kettle, "Sorry to keep you waiting…" There was literally nothing in his voice and Isabelle frowned then looked at the hallway. "Hey, where's your guitar?" Simon blinked then turned around and followed her gaze, "I uh, left it in Eric's van." He said rapidly with slow breathes. _He's hiding something _Isabelle's subconscious told her, but she pushed the thought away. Simon then came over with two mugs of coffee and sat down next to her and then passed her a bright blue mug with white clouds painted on. She took it, "No sugar?" she asked and he nodded. "Thanks" she replied and took a sip then placed the mug down on the table. Jordan walked in through the door with a tired expression then looked up at Simon and Isabelle and then he glared. "Hey Iz," he said coldly as he leaned against the door frame, crossing his arms over his hard muscled chest. "I thought you'd left already." He seemed annoyed with her as he slowly strolled into the kitchen and Isabelle blinked, "You said I could wait here 'til Simon got back." Jordan sighed then opened the fridge and got out some apple juice, pouring it into a glass. "If this is still about the TV then-"

"It's not!" Jordan snapped back and Isabelle jumped from the volume in his voice. What the hell was going on? He seemed totally fine this morning. Jordan glared at Simon who was staring down at the ground looking pale (even for a vampire) Jordan cleared his throat, "Ahem! Simon," he began and then Simon quickly looked up and looked over at Jordan nervously. "We've got that thing to take care of." Simon frowned at him and Jordan scowled at him, "You know Simon, that very important _thing_." Seeming to get the message Simon and nodded quickly, "Right, that thing." He quickly stood up and put his hands in his hoodie then looked down at Isabelle. "Sorry Iz." He said quietly and she could hear he really meant it. Isabelle sighed in annoyance and muttered something to herself before standing up and throwing the blanket back on the couch. "Yeah, sure whatever." Without looking back to say goodbye, Isabelle stormed out of the door and headed out of the building in frustration.

Jordan drove the van down Brooklyn Avenue and Simon stayed in shotgun avoiding looking at him. What happened in the _café_…nothing like that had ever happened to him since…Simon quickly shuddered the thought away and sighed leaning his head against the window watching them pass over Brooklyn Bridge.

"What the hell happened back there?" Jordan said, finally breaking the silence and Simon blinked in surprise then sighed. "I told you, I don't know." Jordan huffed and made a turn, "I thought this was _over _Simon." _So did I…_Simon thought, but avoided saying it out loud. Finally reaching the destination, Jordan and Simon both got out of the van and walked up to the entrance of the very last place Simon would ever want to come back to, Hotel Dermot. Simon felt a chill run down his spine as Jordan raised his hand ready to knock on the door but paused for a moment and looked over at Simon. "You sure about this?" he asked and for the first time since this afternoon, his voice was kind. Simon sighed and scratched the back of his neck, "Do I really have any other choice?" Jordan sighed and shrugged, "Guess not." Hesitantly he knocked twice on the large doors and after a long moment of silence they slowly began to open. Simon and Jordan both peered in and out of the shadows saw a figure leaning against the stairwell with his arms crossed over a leather jacket. It took Simon a moment to recognize that it was Raphael. He saw him grin, revealing white fangs over his lips, "Hola amigos."


End file.
